Hair extensions comprise artificial or natural hair secured to a base adapted to be temporarily attached to a wearer's natural hair or scalp. Techniques include bonding, tracking, fusion, “NoBraids NoGlue”, netting, tree braiding, clip-on extensions, micro braiding, and lace extensions.
Lace extensions are generally limited to full “units” (full wigs or hairpieces). Lace extension units are made from nylon mesh (“lace”) formed into a cap, into whose openings single strands of hair are knotted. Lace extension units can be woven into the wearer's hair by inserting the wearer's own strands of hair through the mesh side-by-side with the extension's hair and knotting the natural hair into the lace next to the extension hair; by sewing into the wearer's hair; or, by gluing the lace edges to the hairline with special adhesives. Lace extension units are relatively flexible and natural-looking, the lace is relatively difficult to detect, and the extension units can be left in place for weeks at a time.
Many people, however, do not need a full extension unit, and often prefer to use directional “wefts”, which are individual, narrow hair extension strips secured to a wearer's head anywhere the hair can be parted horizontally. Wefts are cut to length at the time of application, and are generally sewn or taped to the wearer's hair along the part.
While different types of weft are known, the higher quality ones are generally “skin wefts” using a polyurethane base with the extension hair injected into the base. Skin/poly wefts are relatively stiff, and, although easy to work with, tend to suffer with respect to looking natural. Their longevity also tends to be limited, and they generally must be sewn into the wearer's hair. It is also known to use “tape wefts” with bases taped to the wearer's hair along the part line, but these tend to be of lower quality and their longevity is less than that of the skin/poly wefts.
Lace extensions have generally not been used for wefts. One possible reason is that the knots in a lace extension tend to be more noticeable in a weft than in a full extension unit. The lace is delicate, and would be difficult to cut to length without unraveling and “humping”. Because the openings in the lace tend to be filled by the knotted extension hair, there would be little room for weaving the wearer's hair through the weft, making weaving overly time-consuming and labor-intensive. And, although full lace extension units can be adhered around their edges to the wearer's scalp at the hair line, use of adhesive to secure the hair-supporting base of a lace weft would tend to bleed through the lace and cause the hair to tangle.